Mesh Princess has arrived, only took Sophia 2 days to delivery even right before Christmars, that is impressive.

EML tube is much better bulit compare to Sophia, which mades her (Princess) look like trailer park queen.

Since she just came from out side, glass is very cold, I don't want glass to break from the heat. So I heat the glass up with hair dryer before I drop her in the amp. 1st impression very positive right out of box, but will burn her in at least 50 hours before do any comparision to EML 5U4G Mesh Plate. So far she has some noise, I hope will go away after few hours.

Anyone try National Union 5U4G (circa 1940s)? I just got them off ebay. Wondering how they will sound on the wa22 (one week left in build).

BTW How were your rectifiers packed? Mine were bouncing around inside the white boxes, which bothers me to no end. I would have at least stuffed some paper into the white boxes to prevent damage. =(

I have a NU from around 1951...the date codes are hard to read and decipher but it's very close in sound to the late 40's early 50's RCA black plate. It may even be RCA made and re badged NU....it's a decent performer none the less. Nothing to right home about but miles better than any new production (not the EML/Sophia stuff obviously, just regular 5u4g's) tubes. It should give you a solid top to bottom freq response with good balance. Maybe a slight softness in the lowest registers but nothing to worry about. I like the NU/RCA rec's from this period. They perform well and do not emphasize any one area of the freq spectrum.

These old rectifiers are pretty darned tough so a little bouncing around may or may not cause any damage. I like to see tubes packed well and it I would let the vendor know that his packing method isn't up to snuff.

After trying many sets of top of line driver tubes, 6F8Gs are permanent residents on my WA22, they pair well with pretty much all rectifiers I have but Princess. Now I know why Sophina named her Princess!

The problem:
All my 3 pair of 6F8Gs are pertty much noise fee with other rectifiers: 5AS4, GZ34, CV378, 2x 5Z3, GZ32, and even EML 5U4G. But with Princess, they attract noise like no tommorrow! The two heater wires act like antenna produce very loud hum/noise/buzz. I touched heater wire, then made noise worse. Sounded like an old radio.

I thought may be the large heater of Princess is the source, so drop in EML which has even larger heater than Princess, noise free......

Then I tried 6SN7 and 6FQ7 driver tubes with Princess, noise free......

Crap, I can't use 6F8G with Princess, that broke my heart! When I turn the amp loud, when music overcome the noise, this comb is one of best sound for WA22.

Not too sure, but the tube was tested good when I bought it. I'm new to tubes so not too sure all the details. The bottom of the tube does have some kinda white coating all over, I guess a sign of bad tube?

I don't know if this was answered but the tube lost vacuum and the white "stuff" is the getter that is used to absorb the molecules of gas left after vacuum. When a tube looses vacuum the getter then turns totally white. This is a failure of the tube not from use but from a failure in the glass seal at the base. If there was no sign of abuse the tube should be replaced as a good will gesture.

For me, after comparing the Sophia, the EML and a number of Mullards in NOS metal bass and some fine mid 1950's Mullards, the Sophia is a fairly easy winner. The EML is built like a tank and looks like pure quality. The Sophia is of lighter build quality but has a certain quality that the EML lacks. The Sophia conveys more of the nuance and delicacy of live music, capturing the timber and spatial qualities better. The EML is woodier sounding, less articulate. IMO.

For me, after comparing the Sophia, the EML and a number of Mullards in NOS metal bass and some fine mid 1950's Mullards, the Sophia is a fairly easy winner. The EML is built like a tank and looks like pure quality. The Sophia is of lighter build quality but has a certain quality that the EML lacks. The Sophia conveys more of the nuance and delicacy of live music, capturing the timber and spatial qualities better. The EML is woodier sounding, less articulate. IMO.

Agree, but I can ever get her to work with 6F8G. 6F8G is major upgrade to my WA22.

I'm reading this thread with some interest as I've got a WA6SE on the way from a fellow head-fier. Also, because many of the tubes your futzing about with are crossover to the output stage of my Modwright Transporter, which is very sensitive to tube rolling. Certainly there are a lot of crossover comments I see here..the EML 5U4G is the darling of the MWTP crowd besting almost all comers aside from perhaps the High Wycombe Mullard GZ37 fat bottle from the 40's. Both run around the same price. Dan Wright also had some xtra soldering to do when folks discovered just how good the EML made the MWTP sound, but at the same time tubes were having very short lives. Turns out there was a cap in the path that was of too low a value. The EML wants to see a very specific value there. I can't remember the specifics, but George over at TubesUSA should know (haven't seen this mentioned here - but may have missed it). Without that cap at the right value you may as well stand in a cold shower and rip up the dead presidents while you weep quitely and recite something profound like Rutger Hauer at the end of Blade Runner. We also do the 9-pin > Octal adapter thing because the octals sound better. You can also to to the 7n7 variant with yet another adapter (L-Octal) if you want to save money on tubes. Favorite up until recent was the very expensive 40's TungSol black plate military 6SN7. Theres a Greek dude (fellow named John who goes by Lowbander80 on both sites) on eBay an A'gon who seems to have the mother load and is living high on the retsina by selling them off pair by pair at $300-400 a pair! Damn fine tubes, but may have met their match. You may not like Chinese, but you'd be doing yourself a disservice to skip this tip - Try out the new Shuguang C181-Z Black Treasure tubes in place of your 6SN7's! Grant Fidelity up in Canada imports them. They've supposedly dethroaned the king TungSol and beaten him at his own game. The other one I think you may have already mentioned, is the NOS Russian variants with metal base and round perforations in the plates. There all pretty pricey for the demand. I've got my money on the Black Treasures as folks I know very well have told me the kind of things that brings the wallet out late at night with that zombie-like vacant stare of obedience. There's a long thread on the Modwright section of AudioCircle on tube rolling in the Transporter. It's stickied up to the top... I think it's over 100 pages now. There may be some useful crossover pointers in there for anyone interested. Yeah, I know, different circuit and YMMV, but there are certainly some basic strengths that do cross over. I'm going to hold off on using my EML 5u4G in the circuit (we like to call that one the John Holmes of rectifier tubes - if you've seen one up close and personal you'll know why)...I don't want him going flacid on me before his time. He sure makes that Transporter sing. I have a Princess on the way, a few alternative GZ32/37 and 5AR4 variants to try out too. Thanks for the thread Seamaster. I'm new to the headphone thing coming from my 30-year + chip as an audiophile. Still preferring the impact of my big rig, but the smaller one can certainly be compelling.